Polyester polyrethane foam requires surfactant stabilizers to manufacture foam with good cell structure and an open cell structure to prevent shrinkage but enough stability to prevent form collapse. The surfactants also act as emulsifiers. More and more, the industry is driving to reduced emissions for additives including reduced emissions of silicone surfactants. It is also desirable to move toward higher levels of water in the polyester formulations, but high levels of water make processing difficult often resulting in poor quality foam.
Several companies offer surfactants for polyester polyurethane foam manufacture including Byk Chemie GmbH, Th. Goldschmidt AG and Witco (Europe) SA. As stated in E. Silma et al, "Recent Developments in Stabilizers for Flexible Polyester Polyurethane Foam" (Spring Technical Conference of the PFA, May 17, 1996), p 3, "Silicone surfactants For flexible polyester polyurethane foam are organo-modified polydimethylsiloxanes". This paper also describes a new low fogging silicone surfactant named B8324. Surfactants for polyester polyurethane foam can also be organic in nature and not contain any silicone.
U.S. Pat. No. 4,331,555 discloses a method for making low density flexible polyester polyurethane foam using as a foam stabilizer certain low molecular weight organosiloxane compositions. This patent explicitly covers polydimethylsiloxanes since the backbones contain (Me2SiO)x groups where x is at least one.
U.S. Pat. No. 3,560,544 discloses triorganosiloxy endblocked polyoxyalkylene siloxane polymers with suggested utility as surfactants, wetting agents, detergents, emulsifying agents, fiber lubricants and foam stabilizers for urethane foams.
U.S. Pat. No. 4,751,251 discloses a surfactant composition for rigid urethane foams comprising an organic surfactant. A siloxane-polyoxyalkylene surfactant and water or an alcohol, or both. An organomodified polydimethylsiloxane copolymer which has been capped with dodecyl succinic anhydride is suggested for use in rigid polyurethane foam.
U.S. Pat. No. 5,296,625 discloses silicone alkoxylated esters which contain terminal carboxyl groups as solubilizers.